This invention is a soybean protein film which contains small air bubbles and said soybean protein solution or suspension which contain air bubbles on the flat surface and is dried by heating.
The said soybean protein film has 0.1-0.8 g/cm.sup.3 density and better adhesive property and better taste.
There has been YUBA which is one of the traditional foods in Japan, and this YUBA is manufactured by gathering the protein film spreaded on the surface of protein milk and drying intact.
Dryed YUBA presents a pale yellow and lustrous film like state and is crisp and smooth in surface.
It is necessary to wet a dryed YUBA by water once when dryed YUBA is used for rolling up or wrapping up a cooking material.
Wetted raw YUBA is a soybean protein itself, and is formed on the surface of heated soybean milk.
It is very difficult to preserve a wetted raw YUBA in a state of perfection, as it is roted and so a raw YUBA is only sold directly by the manufacturers or the shops well equiped with cold strage equipment.
YUBA type elastic film is manufactured when wetting agents such as Solbitol and/or Glycerol are added to a Soybean protein solution or suspension and after said solution or suspension is applied to the flat surface, it is dried by heating.
Yuba type elastic film thus manufactured is refered to simply as Yuba type film hereinafter.
This Yuba type film has a better elastic property even if it is dryed, because it contains wetting agents.
Although Yuba type film can roll up or wrap up cooking materials, but it has a fatal defect of no adhesive property.
Furthermore, usual dried Yuba, wetted raw Yuba and Yuba type film have many following defects:
(a) It is necessary for dried Yuba to moisten it with water again, when it is used for cooking materials and this operation is very troublesome.
(b) Dried Yuba once moistened or wetted raw Yuba is not fitted for foods which are requested to avoid humidity, because these have high moisture content.
(c) Dried Yuba film once moistened and wetted raw Yuba film have very bad adhesion property and liable to peel off, for example, for use with boiled rice.
Moreover these films are not rolled up or wrapped up to-gether due to no adhesive property each other.
(d) Although Yuba type film can be rolled up or wrapped up cooking material in dry state but said film is not fitted to use for cooking material due to the defect which have no adhesive properties as described (c) above.
(e) Dried Yuba film, wetted raw Yuba film and Yuba type film are all formed into films due to the binding energy of soybean protein each other, and so these films are difficult to solve in water and bad toothfeeling in mouth due to a feeling of physical disorder and said dried films are felt rough to the tongue and have bad toothfeeling in mouth and especially it is very troublesome due to the coming out of the contents, when the contents are rolled up or wrapped up the soft flowing material for example ice cream, jam or jelly etc..